Alben specifically pointed to an Easton ambulance that was forced to take Richard McGrath, an 83-year-old Easton man with "life-threatening" injuries, to a hospital less-equipped to treat the patient.

McGrath was involved in an early morning crash on Canton Street and the ambulance was en route to a Level 1 trauma center at Boston Medical Center when it was diverted to "Good Samaritan Hospital in Brockton because the highway was shut down and they didn't want to compromise the patient's safety," said Easton Fire Chief Kevin Partridge

"So we have a traumatic injury to someone in a place not related to Boston and that ambulance has to be diverted to another city," said Alben. "That's what I am talking about when we talk about unintended consequences."

"There's got to be a better way than put other people lives in danger, there’s a lot of innocent people out there," said Sean McGrath, who said his father was "pretty banged up."

"I understand the issues, but there's got to be a better way to express it," he said.

The activists were protesting what they call "police and state violence against black people."

The Boston contingent of Black Lives Matter said in a statement that the protest was intended "to confront white complacency in the systemic oppression of black people in Boston."

Pete Frates, who became nationally known through the #IceBucketChallenge which drew attention to ALS, was among many others who condemned the tactics.

"(Col. Alben) mentions unintended consequences. I have and will again need to be taken by ambulance to Massachusetts General Hospital. Today could've been a very bad day," Frates wrote in a Twitter post.

McGrath's family said he is doing much better and reported to be in fair condition at a Boston hospital.